1. Field of the Invention
This invention concerns laminates comprising a polyolefin polymer such as a vulcanized polyolefin rubber or polyolefin synthetic resin and a polar polymer laminated by way of an adhesive layer.
2. Description of the Related Art
Among various kinds of industrial rubber products, since vulcanized polyolefin rubber such as ethylene-propylene-diene terpolymer (EPDM) and ethylene-propylene copolymer rubber (EPM) possess excellent features having outstanding performance, for example, weather proofness, aging resistance and ozone resistance and, in addition, having a wide range of workable temperature from -50.degree. C. to 150.degree. C., they have been employed in various fields as substrates for varius kinds of laminates or molding products. Further, depending on the application uses, there have also have used those rubbers comprising EPDM or EPM as described above blended with natural rubber (NR) or synthetic rubber, for example, styrene-butadien copolymer rubber (SBR), butadiene rubber (BR), isobutylene-isoprene copolymer rubber (IIR), chloroprene rubber (CR), acrylonitrile-butadiene copolymer rubber (NBR), isoprene rubber (IR), chlorosulfonated polyethylene (CSM) and acrylic rubber (ACM), or blended with those resins such as ABS resin, styrene resin (PS), polyethylene (PE) and polypropylene (PP) in various fields.
Further, polyolefin synthetic resins such as PP and PE as described above have also been used in a wide variety of application uses as substrates for various kinds of laminates or molding products such as those parts for use in vehicles or electronic products since they exhibit similar outstanding performance in the weather proofness, aging resistance and ozone resistance like that of the vulcanized polyolefin rubber and are available at a reduced cost.
However, since the vulcanized polyolefin rubber such as EPDM and EPM or polyolefin synthetic resin such as PP or PE as described above have no polar groups in the principal chain of the molecules, they are poor in the reactivity as compared with polar polymers, i.e., synthetic rubbers such as NR, SBR, BR, IIR, CR, NBR, IR, CSM and ACM, or synthetic resins such as ABS resin, PS, vinyl chloride resin (PVC) and nylon resin as described above.
Accordingly, there have been problems in the case of manufacturing laminates by the injection molding of the polar polymer while using, for example, a molding product comprising a polyolefin polymer as an insert, or delamination is resulted at the joined faces by the difference in the heat shrinkage between both of the materials or the migration of plasticizers blended in the polymer. Further, even if a paint or adhesive is coated for increasing the close bondability of the joined faces, there has also been a problem that the painted or coated membrane is defoliated thus leading to the delamination of the joined faces also due to the reason as described above.
This has also been pointed out to the face of laminates manufactured by other molding process.
Although there have been attempted various counter-measures for the above-mentioned problems, no satisfactory solution has not yet been found at present.